Electrical precipitation apparatus



May 11, 19341, J. R. GIES ELECTRICAL PRECIPITATION APPARATUS Filed Jan.23. 1932 INVENTOR.

Jmrasus Pw'mn 6/55 ATTORNEYS.

Patented May 1, 1934 UNITED STATES PATENT OFFICE Jakobus Rafiael Gies,

Frankfort-on-the-Main,

Germany, assignor to International Precipitation Company, Los Angeles,Calif a corpora- )tion of California Application January 23, 1932,Serial No. 588,411

10 Claims.

This invention relates to apparatus for electrical precipitation ofsuspended particles from gases and particularly to a novel andadvantageous form of collecting electrode arrangement for use in suchapparatus.

The principal object of the invention is to provide a collectingelectrode of such construction as to facilitate the collection ofprecipitated material upon and adjacent the collecting surfaces thereofand prevent or minimize dislodgment and carrying away of such materialby the gases passing through the apparatus. Y

A further object of the invention is to provide a collecting electrodeof simple, economical, and rugged construction, and particularly, anelectrode of such design that it may be of relatively light materialwithout danger of undue deformation or warping of the surfaces thereof.

A further object of the invention is to provide a collecting electrodearrangement in which the relation between adjacent collecting electrodesat the opposite sides of each duct or passage through which the gas isdrawn is such as to provide comparatively dead collecting spaces orpockets at intervals along such surfaces.

A further object of the invention is to provide a collecting electrodearrangement in which bafiles or projections may be provided, extendingoutwardly from the surfaces of the collecting electrodes to assist indefining collecting pockets for the precipitated material, withoutappreciably decreasing the cross-sectional area of the gas passages atthe points where such baflles or projections are located, and henceWithout appreciably afiecting the pressure drop through the apparatus.

According to this invention, the collecting elec trodes are of zigzagshape in the direction of gas flow therebetween, such electrodes beingdisposed with the longitudinal lines of the bends or angles thereofextending transverse to the direction of gas flow. A plurality of suchcollecting electrodes are mounted parallel to one another, so that thesalient angles of each electrode are disposed opposite the reentrantangles of an adjacent electrode, thus providing a plurality of zigzaggas passages or ducts therebetween, in which the discharge electrodesare mounted. With such an arrangement, the cross-sectional area of thegas passages is appreciably increased at the regions of the bends orangles, as compared with the crosssectional area at the regions betweenthe fiat surfaces of the plates, thus causing a decrease in the gasvelocity at the first-named regions and providing relatively dead orquiescent spaces or pockets in the reentrant angles, in which the pre-Germany January 28, 1931 cipitated particles may be collected andpermitted to fall to the lower ends of the collecting electrodes and tosuitable receiving means therebeneath, without danger of being dislodgedand carried away by the gas stream.

According to a preferred embodiment of the invention, suitably shapedbaiiles or projections are also provided adjacent these collectingspaces, which project somewhat from the surfaces of the collectingelectrodes in such manner as to assist in maintaining relativelyquiescent conditions in said spaces and in preventing escape ofprecipitated' material therefrom, without appreciably restricting thecross-sectional area of the passages at these points, as compared withthe crosssectional area between the fiat surfaces of the collectingelectrodes.

The accompanying drawing illustrates several embodiments of thisinvention and referring thereto: i5

Fig. 1 is a horizontal section of an electrical precipitator providedwith a collecting electrode arrangement according to this invention.

Fig. 2 is a horizontal section of a modified collecting electrodeconstruction.

Fig. 3 is a similar View of another modification.

Referring to Fig. 1, the collecting electrodes are shown as comprising aplurality of parallel zigzag plates 1 of metal or other suitablematerial disposed with the longitudinal lines of the angles or bends 2extending vertically and with the salient angles of each plate oppositethe reentrant angles of an adjacent plate, so as to define a pluralityof zigzag gas passage ducts 3 through which the gas to be cleaned may bepassed horizontally. The collecting electrodes are shown as inclosedwithin a precipitation housing whose side walls l substantially contactthe two outermost plates at the salient angles thereof so as tosubsantially confine the gas flow to said pas.- sages 3. Said housingmay be provided with an inlet flue connection 5 at one end and an outletflue connection 6 at the other end, whereby gas may be passedtherethrough.

The discharge electrodes are shown as comprising a plurality of suitablyspaced vertically extending discharge members '7 presenting smallsurface area and sharp surface curvature, so as to facilitate electricaldischarge therefrom, in the usual manner of such apparatus. Suchdischarge members, for example, may consist of metal wires or rods ofsmall diameter, and may be supported and insulated from the collectingelectrodes in any suitable manner. Said discharge electrode members aredisposed along zigzag lines extending substantially midway between eachpair of adjacent collecting electrodes, and one or more of suchdischarge electrode members are preferably provided opposite the fiatsurface portions 8 of the collecting electrodes between the respectiveangles or bends thereof.

Suitable means may be provided below the collecting and dischargeelectrodes for receiving the precipitated material falling therefrom,such material receiving means being illustrated as comprising hoppersindicated at 9, whose walls taper downwardly and inwardly to dischargeopenings 10.

It is characteristic of the collecting electrodes of the presentinvention that the bends or angles 2 are relatively sharp instead ofgradually curved, and that the portions 8, between adjacent angles orbends, are substantially fiat or straight instead of curved so that eachpassage 3 consists of a succession of alternate straight portions andrelatively sharp bends or angles.

It will be seen that the transverse width of each passage 3 is somewhatgreater at the region of each angle or bend 2 therein than at regionsintermediate such bends or angles. That is to say, the distance betweeneach salient angle and opposing reentrant angle, indicated at b, issomewhat greater than the perpendicular distance between the fiatportions 8 of two adjacent plates, as indicated at a, so that thevelocity of the gas is decreased as it passes each bend or angle, thusproviding relatively quiescent collecting pockets or spaces 12 at. thereentrant side of each angle or bend.

The apparatus is further shown as provided with baffles or projectingstrips 13 projecting laterally from the reentrant side of each bend ofeach collecting electrode plate, said baffies or strips preferablyextending throughout substantially the entire height of said plates.Said baflies or strips preferably project outwardly only to an extentequal to the difierence between the distance I) and the distance a, sothat the distance 0 between the outer edge of each of said bafiies ofstrips and the opposing salient angle of the adjacent plate issubstantially equal to the distance a. Said bafiles or strips thusinterpose substantially no added'resistance to gas flow, but tend toequalize the cross-section of the gas passages throughoutthe lengththereof, and at the same time serve to prevent or minimize the flow ofgas into the quiescent pockets or spaces 12.

In the operation of the above-described apparatus, a gas is passedhorizontally through the passages 3, for example in the directionindicated by the arrows, and the velocity thereof is maintainedsubstantially uniform throughout. It will be understood that thedischarge and collecting electrode means are connected to any suitablesource of electric current at suitable potential to effect electricdischarge of the silent or corona type from the collecting electrodes.The suspended particles which become electrically charged by the actionof such discharge are caused by the electrical field to move toward andprecipitate upon the surfaces of the collecting electrode plates 1.There may be some tendency for some of the material thus precipitated tobe carried along the surfaces of the collecting electrodes by thefriction of the passing gas stream, but such material is caught withinthe collecting pockets or spaces 12, where it is much less subject tothe action of the gas stream, and these collecting pockets or spacestherefore serve to permit the material to accumulate and eventuallyreactor fall by gravity into the collecting hoppers 9, instead of beingpicked up and carried away by the gas stream. A high efficiency of gascleaning is thus obtained, while the ability of the collectingelectrodes to prevent dislodgment and carrying away of precipitatedparticles permits the gas to be passed through the apparatus at highervelocity than would otherwise be permissible, and consequently increasesthe capacity of a given size precipitator.

A further advantage of the zigzag construction of the collectingelectrodes is that the bends or angles tend to stiffen the same andprovide more resistance against lateral deformation or warping than isthe case with ordinary flat plates. For this reason the collectingelectrode plates may be made of relatively light metal, and the cost andweight of the entire apparatus may be reduced to a minimum.

The construction shown in Fig. 2 is quite similar to that abovedescribed, with the exception that the angles or bends of the zigzagcollecting electrode plates 1' are shown as somewhat rounded, asindicated-at 2 and the projecting bafiies or strips 13 are shown ascurved channels disposed with their open side toward the gas stream, asindicated at 15. As before, the distance I) between two opposing anglesis somewhat greater than the distance a' between opposing flat portionsof the plates and the distance 0', between the outer edge of eachchannel 13' and the opposing angle 2' is substantially equal to thedistance a. The increased cross-section at b, together with the channels13' serve as before to provide relatively quiescent collecting pocketsor spaces 12 for collection of precipitated material and for permittingsuch material to fall to the bottom of the collecting electrodes withoutbeing swept away by the gas stream. The discharge electrodes may besimilar to those above described, and the operation of this form of theinvention is substantially the same as that shown in Fi 1.

In the form of construction shown in Fig. 3, each collecting electrode1" is shown as made up of a plurality of vertical plates or strips 1'?disposed in zigzag relation with respect to one another, and each-ofsaid. strips or plates is shown as provided with a curved flange orchannel portion 18 at the further edge thereof disposed within thereentrant angle between that plate or strip and the next succeedingplate or strip. Said curved flanges or channel portions are concave whenviewed in the direction of gas flow, and the outer edges thereof arepreferably connected to the surfaces of the succeeding strips or platesby means of slightly curved connecting strips 19. Furthermore, thefurther edge of each plate or strip 17 and the curved flange 18 thereofare preferably spaced somewhat from the nearer edge of the nextsucceeding plate or strip, as indicated at 21. By means of thisconstruction, relatively quiescent collecting pockets 22 are provided asbefore at the reentrant angles of the collecting electrodes, andadditional collecting pockets or 1 strip 17 and the outer edge of thechannel 18 of the opposing strip is substantially equal to the distancea" between the fiat portions of said strips, and that the distance dbetween the forward edge of each strip and the opposing connecting strip19 may also be substantially equal to or only slightly less than thedistance 11', according to the relation which it is desired to maintainbetween this forward edge and the plane of the next preceding strip. Itis seen that it is not necessary that this edge, such as indicated at24, project outwardly beyond said plane in order to catch theprecipitated material, due to the relatively sharp curvature of the gasstream inwardly toward said plane as it passes this point.

I claim:

1. In an electrical precipitator, a plurality of collecting electrodesof zigzag shape characterized by sharp angles and fiat portions betweenadjacent angles, said collecting electrodes being disposed parallel toone another with the longitudinal lines of the angles thereof extendingtransverse to the direction of gas flow and with the salient angles ofeach electrode opposite the reentrant angles of an adjacent electrode,each of said electrodes being provided with projections extendinglaterally therefrom at the reentrant sides of said angles and serving todefine pockets for collection of precipitated material.

2. The invention as set forth in claim 1, the outer edge of each of saidlaterally extending projections being spaced from the opposing salientangle of an adjacent electrode by a distance substantially equal to thedistance between the opposing portions of the collecting electrodesbetween the angles thereof.

3. An electrical precipitator comprising a plurality of collectingelectrodes of zigzag shape whose angles extend substantially vertically,with the reentrant angles of each electrode disposed opposite thesalient angles of an adjacent electrode, bafile means projectinginwardly from the reentrant angles of each electrode, said bafile meansextending throughout substantially the entire height of said electrodesand having their outer edges spaced from the salient angles of theadjacent electrodes by a ,distance substantially equal to the distancebetween the flat portions of the adjacent electrodes, dischargeelectrode means disposed between the adjacent collecting electrodes, andmeans for passing gas'substantially horizontally between said collectingelectrodes.

4. In an electrical precipitator, a plurality of collecting electrodesof zigzag shape disposed parallel to one another with their anglesextending substantially transverse to the direction of gas flow saidangles being relatively sharp and the portions of said electrodesbetween adjacent angles being substantially flat, the angles of therespective collecting electrodes being disposed opposite one another andthe distance between the opposing angles of adjacent electrodes beingmaterially greater than the perpendicular distance between the opposingsubstantially flat portions of adjacent electrodes, and each of saidelectrodes being provided with bafiie means projecting therefrom at eachreentrant angle toward the opposing salient angle of an adjacentelectrode and extending throughout substantially the entire heightthereof so as to define a collecting pocket within said reentrant angle.

5. The invention as set forth in claim 4, each of said bafile meanshaving its outer edge spaced from said opposing salient angle of anadjacent electrode by a distance substantially equal to theperpendicular distance between the opposing substantially flat portionsof adjacent electrodes.

6. The invention as set forth in claim 4, each of said bafile meanscomprising a narrow flat strip projecting substantially in the directiontoward said opposing salient angle of an adjacent electrode.

7. The invention as set forth in claim 4, each of said bafiie meanscomprising a channel shaped member having its open side disposed towardthe direction from which the gas is passed through the apparatus.

8. The invention as set forth in claim 4, each of said collectingelectrodes being further provided with means defining additionalcollecting pockets adjacent the salient angles thereof.

9. In an electrical precipitator, a plurality of collecting electrodesof zigzag shape characterizcd by sharp angles and flat portions betweenadjacent angles said collecting electrodes being disposed parallel toone another with their angles extending substantially vertically andopposite those of adjacent electrodes, discharge electrode meansdisposed between the respective collecting electrodes, means for passinggas'substantially horizontally between said collecting electrodes, andbattle means projecting outwardly from the reentrant angles of saidcollecting electrodes and defining collecting pockets lying within saidreentrant angles.

10. In an electrical precipitator, a plurality of collecting electrodesof zigzag shape having their angles extending substantially verticallyand the salient angles of each electrode disposed opposite the reentrantangles of each adjacent electrode, means defining collecting pocketswithin the reentrant angles of the respective electrodes, and I

